I am a 20 year old male. i suffer from anxiety, am on zoloft (sertraline). i have some weird feelings on my left side body for about 5 months, headaches rarely. how likely is a glioblastoma multiforme at my age?

Cant be: Oh oh. You are really imagining the worst possible disaster, so please let your doc know that your anxiety is not under control yet. But that's an easy one to rule out, because gbm is pretty much fatal within 5 months.

20, glioblastoma M.?: Although glioblastoma multiforme can develop at any age, it almost always occurs over age 50. The incidence of it occuring at age 20 is under 0.5/100, 000 (state of ca dept public health). The symptoms include increasing signs of mental dysfunction, new seizures, persistent headaches or evidence that there is pressure inside the skull, such as vomiting. If concerned, get evaluated by a neurologist.

Extremely rare: I would not worry about gliomas as they are rare and often produce severe headaches. Your worry and anxiety is causing most of your symptoms. I would advice that you take daily walks, anytime that you are free. At least once every morning a walk for 1, 2, 3 miles can do you more good than most other things you are doing right now.