I have no idea what it could be, but obviously something is wrong. Get that poor guy to the vet please! Hope he's ok!
Well if hes throwing up hes trying to get something out of his stomach make sure to keep a close eye on him! And if he cant walk or stand hes tired...my dog had this once and she couldnt do anything we had 2 feed her ourselves she was so week! my uncles boxer died last week of this she was suffering alot dont let it get worse! ccuz if it does they will have to put her down..take her to the vet dont let him/her suffer anymore i dont want it to get worse i hope hes okay! :( ill pray for u and ur dog!
BTW: He might get really skinny too