Why do my arms and legs keep feeling heavy? like they are a dead weight or tingly i guess. it happens now and again. it feels like it flares up. what can cause this? blood tests are normally okay. checked for rheumatoid arthritis also and all okay?

You should be evaluated by a neurologist to make sure this is not due to a nerve injury. There are tests that can be done to diagnose a nerve issue. It could also be more of a muscle issue and a rheumatologist may be able to help diagnose a muscle disorder. You likely need more tests and evaluations by neurology/rheumatology to get diagnosed and then treated. Good luck to you!