<s>[INST] Hello, I have a hard small pea sized lump inside my upper lip on the left side. It grew in one day. No chance of biting that area or any other injury. It started to feel as if something had bitten my lip while sleeping at night but by the end of the day it grew into the lump. I would like to seek your opinion as to what could be the cause and what I should do? [/INST] Hello and welcome to Chat Doctor, A small pea sized lump on the lip can be due to bite that you are suspecting or muscle. In case there is history of insect bite, the swelling will relieve after taking antihistamines preparation. In case it does not relieve after antihistamines treatment, clinical examination is required to rule out other lesion like muscle. Mucocele is caused by rupture of mucus glands. Treatment of muscle is by surgical excision. Thanks and take care Chat Doctor.  </s>