Diagnostically, it sounds like the doctors are taking your reported symptoms seriously enough to investigate many different avenues that could be pointing a potential problem. And honestly it could be any number of things right up to perfectly normal nervous system behavior.

How active are you? Do you run a lot? Have you had any previous injuries to the areas? Burns? Scalding? Bruising?

What have they tried to treat the symptoms? Pain meds? Anti-inflammatories? Topical creams? Anti-anxiety? Ice? Heat?

Anything noticeable when the symptoms start? Haven't been sleeping well? Stressed? After eating something? Drinking something? Using something? Remembering something? Trying something?

Does the difficulty concentrating seem associated with the symptoms, or as a secondary symptom, as in you also have difficulty concentrating or is it your symptoms arise when concentrating or do they make it difficult to concentrate?

Equally with the tightness in your chest? Does it seem to occur after you've noticed the symptom of tingling, in conjunction with or act as a separate symptom in that you may have tightness in the chest or you may have tingling in the fingers?

The odd tingling sensation in a fingertip or even muscle weakness in a still growing body doesn't always make the large jump to medical problem. At 23 though it may seem puberty and growing pangs are long since a thing of the past or should be, in your case they may not be. Between 18 and 25 I grew an extra inch taller and I'm a female, but with that growth came some of the same issues experienced in youth when growing, nerves, muscles, and connective tissues still stretching and growing to fit to the longer bones, heart rate as well continued to exhibit a "juvenile " flutter until my mid-30's, something "most" people outgrow before the age of 18.

It may sound a bit less reassuring coming from someone who has MS, however, there wasn't much pointing to my symptoms as being MS at the time and once growth settled down many of those symptoms were relieved. So don't worry too much, or begin a doom and gloom that the doctors will never figure out what's going on, on the other hand don't completely discard it either.

But do try to think of what seems to cause the symptoms to present themselves, and what seems to allievate them. Be mindful of any worsening symptoms, or any new possible symptoms as they may occur and discuss them with your doctor along with possible triggers. Even those of us with MS still tend to have triggers, some of which are completely unavoidable, but a trigger nonetheless to our symptoms. For me, it's raining right now so my muscle spasms are more pronounced which is causing my general feeling of weakness, persistent headache and an overall achy feeling with some mild joint swelling. A few lukewarm showers throughout the day, and an extra muscle relaxer will help alleviate most of it, but every rainy day I'll experience roughly the same increase to spasiisty and the same elevation in symptoms and can allievate them the same way too. Making rain = trigger.... it's not the only one but the list is terribly long and probably incomplete and that's just for spasms.