You seem very worried about this, if in doubt at all, get a test. You can request one from you GP or go to your local GUM clinic. No need to be embarrassed or think they will treat you as some sort of leper, they are very understanding and if you do turn out to have a positive result they will advise and help you. Being HIV positive is not the death sentence it may have been 15 years ago, medication now means someone who is positive can live to 60 no problem. But I hope and pray you have a negative result and whatever has got you worried in the first place i.e unsafe sex or injecting drugs, please be more careful