I seem to be getting palpitations alot, i even get them when i just walk up the stairs, im not overweight i weigh 48kg and im 5ft 3 what's the problem?

May need evaluation: An awareness of your heart beat (palpitations) with effort may simply reflect deconditioning, but one needs to make sure that there is no significant underlying cardiac arrhythmia that is unmasked with effort. Getting a stress test, holter (24 hour rhythm monitor) or event monitor (multi-week monitor) may be in order, as well as laboratory assessment to rule out anemia or thyroid disease, etc.

See your doctor: You may have premature beats or rapid heart beats. If you have them a lot, almost daily, a 24 hour heart monitor should be able to identify them. You may need an echocardiogram to see if your heart is structurally normal. You may need blood tests to be sure your thyroid function is okay and that you are not anemic. Please see your doctor.