Welcome to Just Answer.
When did you notice the lump first?
How large is it?
Does it appear to be inside or in the surface of abdomen or chest?.
Did you get any examination by doctor in last 2 years?
Soft painless lump in this location can be due to a few causes.
There can be a lipoma.
Lipoma is a collection of fat cells.
It is benign in nature.
Other possibility can be a cyst.
Enlarged spleen can cause a feeling of lump but that is usually firm in feeling.
Yes, I would suggest to get an examination by doctor.
Dull ache on taking fatty food can be from gall bladder issues but it is on right side.
Gastritis, peptic ulcer can cause ache on left side.
This is unlikely to be related to lump.
You can take ranitidine or nexium for it.
Please avoid spicy, fatty food.
There may not be any other symptom.
An ultrasound examination can be taken to see the nature of it.
If there’s anything else I can do, please let me know
You are always welcome.