answer:first of all: i'm not a doctor. but the lung pain sure does sound a lot like pleurisy to me. in addition to what you've learned, it can also be caused by dehydration or by a simple common cold, and it frequently sounds and feels much scarier than it really is. the answer to your last question is yes: pleurisy can be triggered by any kind of activity that puts strain on your chest cavity, especially if you are unwell in other ways (sick, dehydrated, tired). the pins and needles and "full" feeling in your arm suggests to me that your backpack doesn't fit you well enough, and you are constricting blood flow to your arm by pinching an artery. this is uncomfortable in the short term, but can be dangerous in the long term. does your backpack have a waist belt? it should, and you should be carrying much if not most of the weight of your bag on your hips. if you don't have a belt on your bag, try carrying the backpack with the shoulder straps way out on the edge of your shoulders, like they're about to slip off. i don't recommend doing that for very long, but it can provide relief to the pinching feeling. the indigestion sounds to me like you're just traveling a lot and changing diets frequently, and your stomach can't keep up. happens to me often as well. but really, it sounds like enough is going wrong that you need to see a real doctor soon. be well, hike safe, and keep us posted!