Thermage should not cause a bumpy stomach. We have yet to see any case of this here at Victoria Park. My suggestion is that you go back to the clinic/doctor that treated you and asking what they can do. If it is their fault, I am not sure based on the limited information; they should fix the area for free.
Start by looking at your before pictures to see if the bumps really new versus just being more obvious with less fat around them. Secondly, check your protocol. Where you taped? (Remember the tattoo like grid that helps guide the doctor or technician along). Finally, have a consultation at another clinic if they are unable to give you educated answers and a proactive plan to fix your problem.
At the Victoria Park Medispa, we know that any esthetic tool needs to be in the right hands, to achieve the best possible results.