Please help me doctor

Back in August I had sex with no condom with a girl i didn't know.  I dont know how long after but it wasnt too long, I noticed a very red small bump on the end of my penis under my pee hole.  I went and had an std test about 2 months after the encounter and it was negative (but they didnt test for herpes).  When I asked the doctor if it could be herpes she said that " She never saw herpes appear that small."  Now when I masturbate I usually feel a little pain after and my penis and scrotum  are almost always red.  I am going to get tested again soon for everything but do you have any idea what the problem is.  The red bump has not gone away since it appeared.

About 2 months ago I had an itchy stomach that ended up breaking out in pimple like red bumps that I could pop open.  Since then they went away but not completely. You can still see red patches on my stomach where they were and a few of them can still have white puss squeezed out of them.

Also about 2 months ago around the same time I noticed a weird feeling on the inside of my cheek when I moved my tounge over on it.  It almost felt like sandpaper.  I looked in the mirror and it was a bunch of little white bumps.  They have NOT left since.  What could these be?

Should I go directly to a dermatologist for all this?  Or get an STD test first or what should I do?
Thank you