After I make poo theres bright red blood on the tissue & the water in the toilet is turned red. Sometimes my bum feels like theres something sharp. Help?

Possible fissure . You might have a fissure which is a tear in the anal canal. This can be very painful. You should keep your stool soft with a high fiber diet and plenty of water. Please see a colorectal doctor or GI to confirm diagnosis and possibly give you a medication to improve your symptoms.
Hemorrhoids. This is pretty typical of hemorrhoids. Try some topical medicine such as preparation h. Should still be checked by your doctor though.