remember to drink lots of water, you get chakkar if you don't drink water.
I was also not eating meals on time and this was happening to me, I went to the doctors but they didn't help, so ghar mein thoda thoda I started eating a bit more even if it was just a small meal or a few bites, eat something that you will like. and then now I have become a little chubby although I am still slim my tummy has become mota!
but drink lots of water and 5 fruit and veg a day. and nuts are supposed to be good too like cashew nuts, by just having these nuts you will put weight on and you won't have any more dizziness!!
I really hope you pass. good luck. you must be very clever to get to 12th std, alot of my fam dropped out by the time they were in 10th!! :)
my dad dropped out after 12th I think cuz he got married to my mum and had to come to england lol....