swelling, edema with Magnesium citrate???

Has anyone had this happen? I have been taking Mag oxide for awhile with no problems. It has been helping me with constipation. I was advised to try Mag Citrate as I have Lymes and it is also supposed to help more with the pain. I started taking it 2 nights ago and also started applying Magnesium oil and took several baths with it in it. Last evening I was at a concert and I drank water ahead of time, but did not drink as much electrolyte water as I normally do. I drank last night but not in excess. I noticed that my calves and ankles were swollen (pitting) when I got home and still are today. The only thing I changed in the last few days was taking the mag citrate..... probably 800 or so a day for the pain I was having and using the magnesium oil. I had previously been taking 1000mg of mag oxide per day. Any thoughts??? As far as I know my kidneys are in good shape.... never have infections or stones, etc. I have very thin lower legs so it would not be overly noticeable but the edema is pitting and my legs feel heavy. I was thinking of countering it with calcium for a diuretic effect....Thanks!