Welcome to health care magic.
1.Possible causes of lump after a
chronic constipation includes venous dilatation which looks like lump and they are generally soft.
2.And hard subcutaneous lump can be hair follicular inflammation / infection.
3.In this case you need to see your GP and get it examined, and if required a
ultrasound to see the nature of the lump, if involving the anus - trans rectal scan will show the communicates if there are there.
4.Treat the constipation , fib ere died, fluids,avoid spicy, junk foods, Home remedy - sits bath ( sit in the tub with warm water )
5.Suggest to get appointment and get examined and treated accordingly as there are quite a large possibilities of complications - which needs operative procedure if delayed. Good luck.
Hope i have answered your query.
Any thing to ask do not hesitate. Thank you.