In Bangkok outpatient clinics are located in hospitals. Stand alone clinics are few and mostly focused on check ups and preventive services (including WellMed).
You should go to the orthopedic outpatient clinic at any hospital. If cost is a big concern then either one of the non-profits or a government hospital -- but the latter, while very cheap will involve long waits, a lot of red tape and initial language barriers so for something like this probably not worth it as a simple consultation and possibly Xray are not likely to cost more than a few thousand baht privately.
Nonprofit hospitals include:
* Mission Hospital near Demicracy Monument
* Camellian Hospital on Thonburi
* Bangkok Christian Hospital on Silom
*St Louis Hospital on Sathorn
Appointment can be made online, by phone or in your case can also just walk in. Tell them you need to sed Dr in orthopedics.
If meds are prescribed do not get at hospital, buy from pharmacy.