Thanks for the query.
I understand your problem and would try my best to address it.
The most likely cause is infected bartholin cyst
which results from blockage of opening of BARTOLINS GLAND.
BARTHOLINS GLAND are pair of glands located near the vaginal opening that secrete fluid and lubricate vaginal lips.
Once these gland become infected,they result in pain.
Your symptoms suggest that you have developed abscess
in your BARTOLINS GLAND and would require a surgical drainage
to clear the pus.
You must consult your doctor for the prescription of antibiotics if the cyst is small however you would need a drainage if the cyst is large and full of pus.
Till you consult your doctor sit in a bath tub filled with few inches of warm water 3 to 4 times a day which should soothe you a lot.
Take pain killers after consulting your doctor since you had gastric banding
I hope to have answered your query however you may revert to me for any further query.
Best of luck