Hello, Thanks for writing to Health Care magic, I am Dr , Muhammad Ahmad , I have read your question closely, I understand your concern and will be helping you with your health related problem. Your symptoms of weight gain, fatigue and leg swelling are consistent with thyroid problem, this is usually caused by low levels of thyroid hormones in the body , called hypothyroidism. I would advise you to visit your doctor regarding this problem he might ask you to get some tests like free T3 ,T4 and TSH levels these tests tell us the function of thyroid gland and levels of thyroid hormones in your body of these are deranged the doctor will get your thyroid medication adjusted and with time you will start feeling better as soon as your thyroid levels get back to normal. If thyroid levels are fine then heart can be looked at by simple echocardiography , heartt function can easily be determined and then medication can be started. I hope this answered your question, If you have more queries I am happy to answer you. Regards. Dr.Muhammad Ahmad