Over the counter pain killers in SE Asia?

We're headed to Malaysia & Singapore in a month or so. I've got arthritic knees and I know we're going to be doing a lot of walking. My knees will put up with a fair amount of this, but it can be a grunt walking through the pain until the endorphins kick in.

I generally manage the pain on a day-to-day basis in the US with Tylenol (Panadol) and either ibuprofen (Advil here in the states) or naproxen sodium (Aleve). I generally carry Tramadol in a prescription bottle which is somewhat effective, and I think I can get diclofenac OTC in Asia (its prescription only here in North America). I've been encouraged in another thread to carry gabapentin as well, can I get that OTC in Malaysia or Singapore, or do I need to get a prescription for it over here before I go?

I plan to have both knees injected with steroids prior to leaving in the hopes of having it last through the trip.