Prozac is FDA approved for that very purpose (just looked it up). If it does do the opposite for you, it will suck temporarily, but you will be ok and there are other options. 
I have an internet addiction too! It is to the point in which I really need to work on it. I am making a few steps like turning my computer off at night if I know that I will be getting home late or won’t have time to check things. Or I go to forums/websites I always visit and make all my reading and replies in one chunk. Thus, I am up to date, but not checking it over all day long. I just went to the grocery store and felt far less compulsive, so I am hoping that the meds will give me a little kick start. Right now, I am waiting for my friend who is always later than I am! >_<.
I actually got a decent amount of stuff done today! yay. probably because I planned it yesterday. victorious! I get very overwhelmed in crowds as well. overstimulation. I have finally made peace with it after doing some intensive research. I go to the club and just accept that I just cannot be present for everyone and relax. Whatever stimuli I can focus on is ok. I can just look around at everything and talk to people when it is comfortable. However, only talk to one person at a time.
ugh..where is he? I hate waiting.