There are a number of ailments that can involve symptoms of abdominal pain in the lower right area. Appendicitis is of course one condition that causes lower right abdominal pain, but once you have had surgery and the appendix has been removed, there should not be any recurring pain. Complications are however possible if the surgery was not performed soon enough or if the appendix was not removed properly, but after two years, it is unlikely that this would be the case; any complications would quite certainly have shown up sooner than this. To be on the safe side however, you should visit your doctor for a thorough check up. Only after a thorough physical check up, examination of your medical history, and possibly after performing a few tests as well, will it be possible to say exactly what the problem is.
It is of course possible that this is an entirely new problem, unrelated to the appendicitis. However, this does not mean that you should take it lightly; pain is always a sign of some problem, and the presence of blood indicates that there is some bleeding too. You mention that you suffer from back pain along with the abdominal pain - this is usually kidney stones indication. However, kidney stones would certainly not cause you to pass blood in your stools. If there is any blood due to kidney stones, it will be in your urine.
Some tumors, cancerous or benign, can also cause the symptoms that you describe. These are not very common, but they are certainly possible, and it is always good to detect and start treating such problems as soon as possible. If in addition to the symptoms you have mentioned, your bowel habits have changed in the last few weeks (or months), there is a greater likelihood of some kind of tumor being the cause. On the other hand, the problem might be much simpler - just a case of constipation, although very severe. This is of course not as dangerous as a tumor, but if the constipation is severe enough to cause bleeding and pain, it requires prompt medical attention. Hernia, diverticulitis, cysts, and a number of uncommon conditions may also be the cause of your symptoms. As mentioned before, the best course of action for you to take is to promptly visit your doctor. Simply being scared on your own is pointless; once you know what the problem is, you can start doing something about it.
answered by G M