Some 530's had lifetime fluid trans and some used Dex II. You need to get that thing to an expert ASAP. If it is a valve body issue, it can be repaired. If it is leaking someplace, you should see red fluid if it is DEX. I think the BMW lifetime is not red but can't say for sure. You certainly need to know what is leaking. There is no dipstick on your transmission so you need to know if it is full of fluid. Not full, could cause a host of symptoms.
Finally, once you get the trans sorted out, every 3 or 4 months, take the cover off the computers on the right side closest to the firewall (4 screws). The second computer from the firewall is the trans. It has a ZIF type of socket on the top. Remove the socket for about 5 minutes and replace. Replace lid. These trans have an adaptive feature that can drive you nuts. By doing this, you clear all the memory so it will function with more performance again. Especially true if your wife drives the car like a little old lady.
Mike Holbrook
Meridian, Idaho
1992 535im, 17", Euro M5 Throwing Stars 8's & 9's, FK-451 235/45s & 255/40s, M5 Sway Bars 25/20, Conforti chip, Lowes Ram Air, glass sunroof