Hey Georgi,
Have you sorted the issue? It’s hard for me to understand exactly the problem just from your description. If you could post a picture it would be useful.
I’m thinking what could be dented? I suppose the skin could be loose which is causing the bridge to sit lower and this would cause string buzz. If this is the case, the skin might have pulled through the tacks due to shock, or sudden humidity changes. Maybe the skin was tacked on too tightly or maybe wood glue was not used when tacking the skin?
Does the neck angle need to be adjusted? You can change the string height by setting the dowel to the rim at a different position.
Is there extra string ends on the tailpiece where it was tied? Maybe the extra bit is resting on the drumhead and vibrating when you play.
I’m sorry for taking so long to get back here, I’ll be checking often for new posts. -Brian