Before we start, I will admit that I didn't bother to look up if my issue has already been brought up, but I am waaaay too busy nowadays....
Anyways, I just got back from boot camp form the Marines last friday, and apparently the Miata developed a coolant leak while I was gone. Keep in mind my car was only started once a week and driven for about 10 minutes per session. I shipped out the last week of January, and one week later right after a big ice storm my Miata had a big coolant puddle beneath it. The coolant reservoir was refilled and afterwards there were no more leaks for about 2 months.
Around the beginning of April the coolant level began to drop rapidly, but there was no leaking. I assume that is simply from the engine refilling itself with coolant after leaking it out. This past friday when I got home there was a big coolant puddle underneath my car, yet the car hadn't been driven in a week. Yesterday I started the car up to see this situation for myself, and after filling the reservoir with coolant, there was white smoke coming out of my tailpipe, so now I'm burning coolant apparently. I filled the reservoir up with water because I had no more coolant and drove around my neighborhood, but there was no leaking whatsoever. Does anyone have any idea what is wrong with my car? After 13 weeks of being yelled at, I juat want to go carve some corners

. Help!