Does anyone know what's wrong with me?

I'm a 16 year old boy, and quite worried. Over the past few months, I've been experiencing a cold sensation on the right side of my head. It's not painful, but really annoying. The past few months have also seen my gait change, in an embarrassing way. I walk in a bouncing motion, as my heels hit the floor first, this radiates up my leg and causes a bouncing movement. Recently, I've been muddling my words a lot, sometimes merging two words like familiar and similar, creating samiliar (this only occured once, but still!). I've also been a lot more tired, sometimes feeling lightheaded. I have already come up with a list of things that may be attributing to these problems, and these might help you guys give me an answer as to what is wrong with me. I've been carrying an extremely heavy school bag (one strap) for a good 4 years. This has led to having a neck problem - I became aware of this as my neck makes a clicking sound when I turn it - and may have induced a funny walk, considering it's hurt my back as well. My diet isn't the best either; I've made efforts with my five a day but eat A LOT of garbage. This may lead to me feeling tired as well as the fact that I rarely get my eight hours of sleep a day. Reading up on getting mixed with my words, I found that a lack of adequate sleep can lead to being at a loss for words, something I hope is the case here rather than something serious. What I'm really confused about is the cold sensation on the right side of my head. Incidentaly, my neck makes a clicking noise when I turn it to the right, but not the left. Does this mean that something may be out of place at the top of my spinal chord?? If so, this could link back to a funny walk, not sure. Please help!