Usual blood clot like small red bumps in mouth due to teeth bit or mostly during chewing , goes away automatically after some time. i am a smoker.

Red bumps: First, you should stop smoking as it's a known carcinogen and will also lead to other health problems. While it seems that you have diagnosed the red bumps as related to accidental trauma, without actually examining you, we can't confirm or negate your diagnosis. It's best to have this checked by a local dentist (or physician).

Red bumps: As you are a smoker I would strongly suggest that the nest time a red bump appears that you have it examined by a General Dentist or an Oral Surgeon.