Can mono cause nausea or a late period? or is this even mono?

I have felt VERY nauseated for about 8 weeks, I also get hot flashes, loss of appetite, fatigued, when I can eat I get full very fast, I have thrown up 3 times since I've been feeling this way, I have swollen glands, get headaches, stomach cramps, and I feel very weak. It sometimes goes away for maybe a day or 2 but always comes back... I'm starting to get used to feeling like this but it's keeping me from doing things I usually would like hangout with friends, going on jogs, clean around the house, go shopping and etc. My best friend had mono right before I got it, so that's why I think it's mono and we called the doctor and they said it could be either mono or pregnancy (and pregnancy is not possible because I am not sexually active) I have also been very stressed out and depressed lately, not because of sickness, but because of school and a death of a friend so maybe that's the reason? Now that school's been over for a few weeks I thought it would go away, and it did for a couple days but came back right after. This is really scarying me so please help in any way you can. I'm a 16 year old female and have never felt this way before, and have had mono about 2 times before this and it feels way different. I used to take zinc pills but stopped when I started feeling sick. And there aren't really any times where I feel extra nauseated it's usually the same level throughout the entire day.