What Causes Heavy Watery Discharge?

i recently started having a heavy discharge (or urine, not sure which) but it is clear and thin. i can put on clean panties and an hour later they are soaked as if i urinated, but i didn't feel it. when i do my laundry, my colored underwear have spots as if bleach has come into contact with the crotch of the underwear, but it hasn't. a little history - i'm 27 years old. i never had any discharge before (other than the occassional which had no odor or color). i have 2 children (both c sections) and i've also gained a significant amount of weight within the past 2 years. i went from 155-160 to about 220-30 lbs. the weight gain was due largely to drinking alcohol. i worked, went to school, and was a single mom - so i became quite depressed last year when i graduated and could not find work after 4 years of such sacrifice and efforts. i know drinking is not good for me, but i wonder if it may have anything to do with the discharge? my underwear smells horrible, but my vagina itself doesn't seem to emit the same odor. also, after my underwear dries, it doesn't have the foul odor - only when it is fresh/wet. also, i've been with my partner for six years and a there have been two occassions (just before i noticed the discharge/odor) that we had intercourse and it seemed as if i had urinated during intercourse. the first time i thought maybe HE really did urinate on the sofa because it was a HUGE puddle of liquid (but no odor), but the second time - i realized it had to be me. i thought maybe my orgasms/excretions were changing since i'm getting older (or i had a TRUE orgasm), but shortly after these instances - the discharge and odor started happening. there is no itching or burning, but there is a rash in the folds of my thighs (between my vagina/thighs) and i wonder if it's because of the extreme/rapid weight gain, the alcohol drinking, or something more serious? btw, i drink mostly every night - at least six beers or more - and have been doing so for several months. i was very active before and worked out/dieted every day - and this has scared me into getting healthy again. please help!