arthritis triggered by dietary protein, and water

I have the oddest problem, which began about a year ago. I get joint pain after eating foods high in protein (chicken, fish, beef, legumes), and after drinking water. The joint pain from eating protein-rich foods lasts longer, and tends to be more extensive, than that which comes as a result of drinking water. The joint pain from the water is mostly mild twinges in my elbows. The pain from protein-rich foods is in elbows, ankles, fingers, toes, shoulders, etc., and lasts until the following morning. I have been eating an alkaline diet (pH Miracle plan) for about a week, and after testing my water and seeing that it had a pH of 6, I've been adding baking soda to the water. So far my joint pain hasn't changed at all: I eat lentils or beans, and the pain comes. I drink water, and I get the sharp, hot twinges.

Does anyone know what I might do, or what might be causing this? I don't think it's a result of food intolerances , since the joint pain doesn't discriminate between protein sources, but only varies with AMOUNT of protein - the more protein I've eaten, the worse my joint pain will be.

The nature of the joint pain is like a burning, sharp pain. It is not the dull, deep ache of osteoarthritis (which I have in my knees and which is totally different). And it seems to move, like, one minute my fourth finger hurts, the next minute my elbow, and the next it's my ankles and one of my toes. It's migratory, I s'pose we might say.

The pain was only in one elbow, last year, until I tried the Primal diet, during which the pain spread to every joint in my body and became extremely painful. After discontinuing Primal eating, I did an elimination diet, eating only the handful of foods which almost nobody reacts to, and that alleviated the pain by about 70%. So I'm doing okay, now, but would like to eliminate the rest of the pain.

Why on earth? Dietary protein, and water, of all things?!

BTW, my rheumatoid factor came back negative. Xrays of my hands showed inflammation, but no joint damage. My vitamin D was low, so I began supplementation, and now my level is well within the healthy range, but my symptoms persist.

Thanks tremendously for any help with this.