It's great that the blisters on your penis have stopped appearing after taking antibiotics for a UTI. Bacteria can potentially cause various symptoms, including skin issues like blisters in some cases. It is possible that the antibiotics you took helped eliminate any bacterial infections contributing to both your UTI and blister issue. However, without proper testing and diagnosis by a healthcare professional, it's challenging to definitively determine the exact cause of those blisters.

If you experience similar symptoms again or have further concerns about STDs or other health issues, seeking medical advice from a doctor would be advisable for accurate evaluation and appropriate treatment if necessary. If there are more specific questions related to this topic or another concern you'd like information about as an STD assistant feel free to ask!