Severe left sided lower abdominal pain
associated with nausea
suggests that you might be experiencing an attack of Diverticulitis
These are small pouches or pockets from the wall of the lining of your
colon or the large bowel. You are at the age that we see this more commonly.
Since you mentioned that you had gallbladder
surgery before, I can be very
certain, if you have a CT-scan of your abdomen, they will find diverticulitis.
There are different levels or grades of this condition, any where from mild
to severe with complications such as abscess
, bleeding or even rupture.
I also don't like the fact that you have lost weight without trying.
I suggest that you see your doctor as soon as possible to have blood tests
and the scan done. Only after that you can get the appropriate treatment.
Wish you well.