Yes, there is something wrong. It is just not that you are getting older and bound to get this.
The causes for swelling in the feet could be:
4. Local causes
Please get the following specific investigations done to conclude on the cause, if not done earlier.
1. ECG - to see if your heart is normal
2. Blood urea Nitrogen (BUN) and serum creatinine
to look at the kidney function
3. Fasting thyroid profile
4. Serum albumin
to look for hypoalbuminaemia
If these are normal, then we could say it is probably a benign condition, which will go away eventually.
Meanwhile, you need to treat it symptomatically with foot end elevation and crepe bandage.
The fluctuating high heart rate
is a concern. If the ECG is abnormal, do get a echocardiography
of your heart done.
I wish you recover soon and lead a normal life again.