Hello, Foremost of all I m unable to know your age. Considering the fact that you mentioned, your doctor said that you do not have arthritis , I m assuming that you might be around 40 s. From my perspective I would first advise you to have a radiographical investigation of your knee to make sure the prime cause of pain. It can be either from your knee lagging ligamentous support or something dealing with the joint itself. For symptomatic relief of pain you can take ibuprofen tablets available over the counter twice a day after food. Be cautious if you have ulcer or gastritis as ibuprofen by itself has the tendency to cause ulcers. I do not personally find a correlation between your increased blood pressure as a cause for the joint swelling; However, follow simple dietary measures and physical activity to keep your blood pressure in control. You can try using knee caps/braces to provide support to your joint. Finally I advise you that seek radiological investigation at the earliest to arrive at a conclusive diagnosis.