What Causes Nausea,heartburn And Headaches While On Medication For Hyperthyroidism?

Hi. I am 29 years of age and have had Hyperthyroidism for around a year and a half now (with large Goiter) I’m currently taking Polythiouracil, Propranolol and Naproxen (Naproxen only when needed as neck becomes painful at times) Now, my monthly cycles have varied over the past year and have become very irregular, for me anyway. I used to get my period every 38 days and have them last 7 days. Recently I can get my period anywhere from day 26 to day 38 and still last for 7 days. The only tim les I have ever gone over the 38 days, I was expecting my children. My last period was on the 15th October and now on the 26th November. My question is, could any of the medication I’m taking cause a negative pregnancy test? I have had heartburn, frequent urination, headaches, cramps, sleepless nights and nausea. I’m not now nor have I had any illness or infection recently. I have 3 children so am aware that this is abnormal for me to feel this way. What would you suggest I do please? It’s extremely frustrating that i don’t know the cause of this issue for certain. Thank you.