As I'm sure you've noticed, we have 2 new subforums ('Friends, Family and Work' and 'Mental Health'). We've also changed the name of the original H&R forum to 'Relationships' so that there is an obvious split between Health and Relationships. For more information about the changes, see this thread.
Anyway, here is a brief guide of where to post different types of thread. If you're unsure, don't worry, you can either post here for advice or pick the one that sounds best.
General medical complaints e.g. illness, injury.
Quick queries relating to symptoms or diagnosis (remember, all advice is unprofessional)
Threads about medication and first aid.
Threads about using the NHS and other healthcare systems.
Threads about eating disorders (consider posting in Mental Health)
Thread about long term medical issues.
Contraception and fertility (although if it's to do with side effects of contraceptives you might want to post in Health).
STIs, their symptoms and their treatment.
Health during pregnancy.
Sexual dysfunction e.g. premature ejaculation, inability to orgasm.
Mental disorders (e.g. Schizophrenia, Bipolar Disorder, Psychosis), their symptoms and their treatment.
Depression or feeling down/depressed.
Self-confidence issues (although consider posting in the Relationships forum).
Relevant medication e.g. anti-depressants, beta blockers, anti-psychotics.
This is not an exhaustive list. Feel free to use your own judgement and, if you really can't decide, post here and a mod will tell you the best place to post.
See also this thread for where to post in Relationships and its subforums.