I.
It is permissible to take medicine to bring on menses subject to two conditions:
Firstly: it should not cause any harm.
Secondly: it should not be a trick in order to waive an obligation such as fasting.
Al-Bahuti (may Allah have mercy on him) said: It is allowed for a female to take permissible medicine to bring on her menses, but not when Ramadan is approaching as a trick to avoid fasting, like travelling so that one may not fast.
End quote from Kashshaf al-Qina`, 1/218.
Based on that, it is not permissible for you to take medicine to bring on your menses at the beginning of Ramadan so that you can not fast, whether that is because of exams or otherwise.
II.
It is not permissible to not fast because of having exams, whether by means of a trick or otherwise.
Shaykh Ibn Baz (may Allah have mercy on him) said: It is not permissible for the accountable person to not fast during Ramadan because of exams, because that is not an acceptable excuse according to Islamic teachings. Rather he must fast, and study at night if it is too difficult for him to do that during the day.
Those who are in charge of exams should be kind to the students and not schedule the exams in Ramadan, so as to serve two interests, namely fasting and making it so that the students can focus when preparing for the exam. It is soundly narrated from the Messenger of Allah (blessings and peace of Allah be upon him) that he said: “O Allah, whoever attains any position of authority among my ummah and is gentle towards them, be gentle towards him, and whoever attains any position of authority among my ummah and is harsh towards them, be harsh towards him.” Narrated by Muslim in his Sahih.
My advice to those who are in charge of the exams is that they should be kind towards the students, male and female, and not schedule exams in Ramadan; rather they should schedule them before or after that. And we ask Allah to guide and help us all.
End quote from Fatawa ash-Shaykh Ibn Baz, 4/233.
III.
The healthy student who is not travelling is obliged to fast Ramadan and to form the intention to fast from the night before. It is not permissible for him to start the day not fasting; rather he is subject to the ruling that the jurists mentioned regarding those who do physically demanding jobs; the ruling is that they are obliged to fast, then if it becomes too difficult for one of them to continue fasting during the day, and he fears that his health may be damaged or that he may die, he should break the fast by eating just enough to ward off hardship, then refrain from eating and drinking for the rest of the day, and he must make up that fast.
It says in Sharh Muntaha al-Iradat, 1/478: The one whose work is physically demanding, and he may suffer harm if he does not work but he fears that his health may be damaged, may break the fast and make it up later on. This was stated by al-Ajurri. End quote.
In Al-Mawsu`at al-Fiqhiyyah (28/57) it says: The Hanafis say: For one whose work is physically demanding and he needs to earn a living, such as bakers and harvesters, if he knows that if he does his work he will be harmed to the extent that allows him to break the fast, it is prohibited for him to break the fast before he encounters that level of hardship. End quote.
It says in Fatawa al-Lajnat al-Da’imah (10/233): In the case of one for whom fasting is obligatory, it is not permissible for him to break the fast during the day in Ramadan just because he is working, but if he faces great hardship that leaves him no choice but to break the fast during the day, then he may break the fast and eat as much as will ward off hardship, then he must refrain from eating until sunset, then break fast with the people, and he must make up that day on which he broke the fast. End quote.
So seek the help of Allah, may He be Exalted, and put your trust in Him, for Allah is able to make things easy for you and He is able to ward off hardship from you, enable you to understand easily and achieve (in your studies) that which has never crossed your mind. He has promised a goodly provision to the one who fears Him, and He has promised that He will suffice the one who puts his trust in Him. Allah, may He be Exalted, says:
{Whoever fears Allah, He will grant him a way out [from difficulty], and will provide for him from where he does not expect. Whoever puts his trust in Allah, He will suffice him. Allah will surely attain His purpose. Allah has set a measure [and appointed term] for all things} [At-Talaq 65:2-3].
And Allah knows best.