Hello.. It is a very common problem faced after delivery.. It is known as Anal Fissure which is basically a cut or tear at anus due to increased pressure.. The lump u r feeling is called Sentinel Pile... The problem of pain can be easily solved by using some herbal medicines.. The lump can not be dissolved through medicines.. Chances of recurrence are high when it is treated through medicines.. U hav to maintain ur hygeine and take a lot of fibres in ur diet.. Avoid straining while passing stools.. For safe and permanent cure u need to undergo a minor parasurgical procedure known as "Kshar Sutra Therapy" .. Or u may opt for surgery as well, although there are some risks involved in surgery... Kshar Sutra Therapy is safer and effective.. Wish u lots of health..