What should i do about my flattening feet?

Much depends on : What sort of symptoms you have. If there's pain developing, then most of the time the situation can be helped by the used of custom orthotics. Its all about the stability of the feet more than the literal height of the arch.

Orthotics : Are a good thing to try if you have not already. There are over the counter and custom made versions depending on severity of the deformity. If they don't work and you still have pain there is always a surgical option.

Nothing: If they are symptomatic then there is treatment.