Well, bummer that your mom isn't listening and helping. Hey, when you are in pain, it's hard to focus on school. I get that. I'm not sure what co comedal is, like ibuprofen? It should take edge off. If this continues, I assume you go annually for a doctor's well check? My kids do as do I. That is a good time to ask about this situation. Or if you have an aunt, sister, etc. It's hard to know what is going on as it sounds like pressure and cramps down really low but that would generally be the signs of a period coming. But hard for me to know for sure.
Sorry you are having this pain. I have a son in high school and I know that missing a day of school is a set back! So much is covered and missing can mean getting behind even if you're only gone one day. So, here is the thing. At your age, you have an excellent resource at your disposal. Your mom! She needs to know. You may have pressure there because of your period as you say but tell her. She will monitor, take your temp, give you ibuprofen which works for pain relief and then take you to the doctor if this doesn't improve. Have you talked to your mom? Like I said, I'm a mom and things like this are mom territory. Don't be embarrassed--- helping you with this stuff is part of her job. :>)