Thyroid problems? No insurance.?

Lately I've been worried. About 5 months ago, I noted a little "m" that moves in my neck, just above where it would be the Adam's apple. I do not have any symptoms in my neck - no sore throat, no hoarseness in voice, etc. I also noted that I've gained weight, even when I'm watching what I eat. In the last menstrual cycle, my period came for only 3 days, and it was a brown discharge (sorry for the too much info). This month I'm a week late. I took a pregnancy test last month and this month, and both negative. That, coupled with the fact that I don't have any other "pregnancy symptom" (I've been pregnant 3 times) makes me think that I'm definitely not pregnant. I've also been very tired lately, but that could be from all the hours I've had to work lately. My question is, has anyone had weird discharge and missed periods with thyroid problems? Is it possible to have a thyroid nodule that way up in the neck? The first thing I thought about was thyroid, because seems like a high percentage of women on my dad's side of the family have had problems with the thyroid (my two sisters, three aunts - two of which had cancer and one died, cousins, etc.). Anyone can think of anything else? I've also been kind of lightheaded lately, like I can't think straight. I have no insurance and believe me, it's impossible for me to go to a doctor and be able to afford all the test the doctor for sure will order (I currently live in Houston, TX, way more expensive than my hometown in Puerto Rico). I also have celiac disease and routinely suffer from migraines, but other than that, I don't have (that I know of) any health problem. Has anyone had the same symptoms?