Many Symptoms, Beginning to Worry Yet Again- Please Help :/

Recently I decided for no apparent reason to research hiv, causes, symptoms, etc. Since that time I have been worrying non stop and thinking of every little possibilty that I could have it. I fear death for sure and I think I may be worrying too much. I have muscle aches very frequently, mostly in my arms and legs. Headaches, heart beating fast, etc. I found out also that I have an anxiety disorder. I got tested for hiv awhile ago and found out it was negative. But I thought of another possibility when I gave oral sex to someone for a duration of maybe two-three minutes and no ejaculation, and very little pre cum if any. The test would not have covered that episode. So I am worrying myself sick. I am also a hypochondriac and partly depressed. I hardly exercise and don't eat very well. I got mono 4 1/2 months ago and recently started to get over it. My lymph nodes in my neck are now swollen and it's scaring me that it can't be mono, and I feel like in my head for sure it's hiv. Please help. I actually picture like dying and stuff and how i'll hurt my family and friends. It's ridiculous and I can't take it anymore. I am going to go on medications but I need some reassurance. The only thing really making me think I have this is the swollen lymph nodes. Can mono still cause this stuff to happen from stressing out so much? Or maybe I have chronic fatigue syndrome? Please help, I can't take this. Much thanks <3