You’re young and unless there’s underlying medical issues I wouldn’t think it’s anything serious. My whole body used to get really sore and I’d get bad back pain for no reason (so I thought). What solved my issue was a combination of eating better and that doesn’t mean just your typically fruits and veg. Cutting off the junk food, microwave meals, fast food, etc. will help increasingly in how your body feels and even your mindset. Drink lots of water, and if you’re willing to go the extra mile, strictly water. Also, stretch every morning/day, before seshs, etc. stretching is important and will help ya feel more comfortable on your bike. It seems like a lot but it’s very much so worth it. You’re young so I don’t expect ya to go head first into a healthy head lifestyle but my advice is to take care of your body and you’ll feel much much better. Keep rippin dude:)