What Causes Petichiae?

Hi, I'm a 41 year old female with a recent history of low platelets. Mine are about 119,000. I have petichiae from time to time and it worries me. I have a history of migraines and after having a 'complicated migraine' was forced off bc pills and now have a Mirena IUD. I also take Zyrtec (10mg) and 50mg spironolactone daily (for acne). Other than that, I am healthy with normal BMI, 5'4.5", weighing 127lbs. What could be causing the low platelets? They were not discovered until after having children (almost 9 years ago). I am eating red foods, which are supposed to increase platelet counts. Every time I drink an alcoholic drink, I noticed more petichiae - so I dont do that often... but it is the holiday season...