Brief Answer:
Tummy Tuck may not be related.

Detailed Answer:
Hi.
Thanks for your query.

Read and understood the history.
To recapitulate: Female / 62 years - tummy tuck several years ago - sudden occurrence of - stomach become hard and a bit swollen, feeling tight - seems like
the stitches in the stomach have become tighter.

Since the tummy tuck was done several years ago, the chances of the surgery in the past may not at all be related to the present problems.

The hard swollen appearance might have been due to some intestinal or other problems like intestinal infection with gaseous distension.
This need to be investigated as discussed:
Get a clinical evaluation and physical examination of the abdomen done by the Surgeon.
Ultrasonography of the abdomen, X-ray of the abdomen in the standing position, related tests of the blood, urine and stool helps in some cases. If required a CT scan may be done. Other tests as needed.

By doing all these things as explained, one can get to the root cause of all your present problems and can be treated accordingly.

I hope this answer helps you, please feel free to ask for more relevant questions or if you feel that there is a gap-of-communication.

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Brief Answer:
Gastroenterologist will be a better option

Detailed Answer:
I would advise you to go to the Gastroenterologist, considering the symptoms of
> all of a sudden the stitches in stomach seem like they have become tighter and stomach has become hard and a bit swollen; it doesn't hurt so much as feel very tight.

There is a chance of an early diagnosis and proper treatment.
You may please ask any further relevant query if you have; may rate this answer before closing.
I will be available on the link given below if you need my opinion in future.
http://bit.ly/askdrtchandrakant

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