[latebloomer]

The clinic you're looking for is called the Department of STD Control or DSC for short. It's located at the old Kelantan Polyclinic site, the poly having been shifted to IOH at SGH.
It has just completed renovations recently. The name of the road is Kelantan Road, but actually the road in front is called Jalan Berseh.
Landmarks nearby: as you go along Jalan Besar, look on you left for a McDonald's located at New World Centre. After that is Berseh Food Centre. If you come by bus, you should be alighting now. The road after Berseh Food Centre is the one you want. Walk in and you should see the glass frontage of the DSC clinic.
The DSC is the best place to go for complicated STDs, cause all the investigations can be done under one roof. Also you get to consult STD specialists.

BTW, if what you have is genital warts, the treatment done there is using liquid nitrogen. That is the nitrogen we get in the air, chilled at minus a few hundred degrees, until it becomes a liquid. As it's applied on the warts, the extreme cold will kill the viruses causing the warts. However, the treatment may be slightly painful and take more than one session to be complete.

One more thing: the motorcycle spare part shop is Lim Ah Boy's. It's opp the coffeeshop where the famous laksa store is at.