What kind of medical problem am I having?

So, I'm 13, and I don't feel that great. My joints feel like they're tightening/stiffening and I'm sore all over my body. I've had a headache for the past few weeks on and off too. My mom said I might have lyme disease, but I checked for a rash and I saw none. Simple every day actions like walking up the stairs or even coughing are somewhat painful now and I move slower because my knee joints and arm joints are sore and slow. What kind of problems am I having?