itchy scalp & anus, hair loss, bouts of diarrohea &

So as you can see from the above i really need some help.

I have an itchy scalp, my hair is falling out, not in patches, but when brushed or washed it comes out in 15-20 strands at a time in my hands.

I have an itchy anus and bouts of diarrohea, especially directly after eating food, not daily but this comes and goes.

I don't know if this is connected but i often wake up feeling puffy and have odd outbreaks of small spots on my face and back.

Lastly i have had painful sex for as long as i can remember and am starting to get really depressed about it. I have had the same partner for the last 2 and a half years and before then as you can imagine was not particularly promiscuous.

Please let me know if you have any idea what is wrong with me. I am generally a very happy person but this is really starting to get me down.

Thanks