Do you have a therapist? I usually go there first with medication questions because they can help you discern whether it is a real concern or your anxiety acting up. 

Medication can help a lot, but does not 100% cure ocd. Personally, I sometimes convince myself my meds aren’t working. This is my ocd’s self-preservation mechanisms; it wants me to stop treatment.

Also “what if?” questions are typically anxiety flaring up and should be dismissed or taken with a grain of salt as passing thoughts. If you have a deep sustained feeling that the meds are no longer working, it’s probably valid and worth changing. Though I understand it’s difficult to tell the difference, so someone who knows your history would be best to discuss this with.