Am i ok? i got paranoid after reading stories about testicular cancer. i went to a urologist 2/3 weeks ago. he said everything's fine. i was relieved. but after a few days i began paranoid again. so, could something have happened during these 3 weeks?

Yes, things can happen during 3 weeks, however you should seek medical help for health related anxiety and obsessing around subjects that you study. Start with your pediatrician or family doc.

It is not feasible to provide a meaningful opinion without taking additional history, physical examination and may be some tests. It would be prudent to see your doctor and discuss if you may be depressed. Counter-intuitive as it may seem, exercise may help. Start with low intensity exercise such as walking and gradually increase the intensity as tolerated. Drink more water. Wish you good health!