Health problems. do you recognize My symptoms?

the problem is when i am on my feet walking around. or sitting for a wile too. but mainly when i am on My feet. what will happen is when i first start walking around i am fine. feel great. about 15 to 20 mins on My feet i start to sweat for no reason. i get weaker and weaker. and My gut will knot up. after My gut knots up My legs fall weak like noodles and then My heart rate just races 200+ bpm. at this point i usually collapse. i have been checked out more than once during one of these attacks. My blood pressure is very high during these symptoms alone with the fast heart rate. after one of these events happen i usually don't feel any better till after sleep. sleep almost acts as a reset button for these symptoms. i have seen doctors and so far no answer. they have ruled out anxiety. that's what they thought it was at fist but they ruled that out. they ruled out heart problems too. they have not ruled out anything else yet. do you have any idea what could be wrong? do My symptoms sound familiar to you? i am also gaining wight. and i have also been having issues with My joints. all of them. My ribs My shoulders My neck My spine everything. they stiffen up and when i move them they have this crunching popping sound. it get is in My muscles too. i will get a stiff neck and when i tilt My head the neck muscle itself will crunch and pop its almost as if My muscles are solidifying themselves. its hard to explain but that is the best description i can give. what the heck is that? i also have had a stress test done. 2 mins and i about collapsed. super high B.P. and heart rate. i used to Be an athletic. i played baseball raced BMX ran track. so that stress test was really not good. but they couldn't tell Me anything. They said the heart looked fine. i need to see some other specialist. That is the answer i keep getting. i go in i have some test and they always tell Me go see somebody else or refer Me to another dr. but round and round i go nobody i see has an answer.