hello, your condition may be a neuropathy. feeling your heart beat is called palpitation, it can be fast or slow. fast hear beat leads to formation of blood clots which gets lodged in various organs like brain etc causing limb weakness. if the heart beat is slow you will feel light headed, sweating etc. pain in the joints can be due to the inflammation of the joints called arthropathy.a definite diagnosis can be made only after clinical examination and relavent investigations. i would advise you to meet your physician regarding this. a clinical examination will help to understand the pain and weakness. a simple EKG will help to know the functioning of your heart. if all turns out negative then this might be due to anxiety alone which can be treated. i hope i have answered your query. take care