No, not a weird stage.
Please read my not to nymom815. More than half do not get bull's eye rash, nor remember a tick bite.
Usually those are tree ticks or it may have been rocky mountain spotted tick but it sounds like your son may have Lyme I am learning as we go here I would insist on at least two blood tests and don't take no for an answer!!!! First test Lyme Elisa and the second a western blot. While doing those I would ask for ANA and PT, INS, CBC, CMP. These are some basic tests that while they are pulling blood they may as well want to check. It sounds like Lyme and in only about 50% of cases does a bulls eye show up. But like I said it doesn't sound like a deer tick. They are itty bitty. I mean like tiny small. Smaller than a flee. I've heard of other ticks causing lyme and your son may have been bitten by a deer tick it could have fallen off and then you wouldn't even know. Good Luck with your son and I hope that all works out. Always follow your intuition with your child. First or not if they aren't acting right check it out.