Thank you Daren & Alan for taking your time to type out so much!!
I had basically washed the exterior of the P37, the maroon/chocolate cover, the plastic cover covering the reeds and the rubber seal with dishwasher soap and left it under a really scorching sun for 30 mins until it was completely dry. I had wiped the reeds gently with a cloth and left it indoors for about the same time before covering everything up.
What happened afterwards was that I did some finger practices, such as arpeggios which involved running around the same few keys alot. Guess that contributed greatly to the build up of spit. Ever since, I have been playing less of these finger exercises and just normal pieces. The choke happens once in a while but doesnt linger on like I did at the time of my original posting. Likewise the same occur from some notes which had some excessive ringing. I did not widen or flatten any of the reeds throughout this period.
Regarding how often I empty my spit, I guess its a habit to clear whenever possible from years of brass playing. That being said, it initially seemed as though my P37 had a leakage problem. I couldnt figure out why a river of saliva coming out from the last key when I inverted my melodica, until opening it up. If i had the resources, I would definitely reworking the exterior case and modify the 5 screws reeds cover plate like Daren did.