Please Read! I need advice SUPER bad!?

My 15 month old son is the happiest, most content little boy I have ever saw in my life. Today he was very happy, playing, giggling as usual but about an hour ago he all of a sudden started vomiting, ALOT. So i gave him a warm bath, dressed him, & gave him some ibuprofen. He SCREAMED and squirmed as if he was in severe pain for a good 30 mins. He vomited again, and had the dry heaves for about 5 mins. Now he is quiet but doesnt seem to have any energy, wont smile, just so lethargic and his eyes are all sunken in and look awful. He also had alot of bowel movements yesterday, very liquidy. As of right now, no temp but then again he has had ibuprofen. I'm just looking for some advice because he is my first child, and since there were no warning signs, it just happened so fast, it scared me. So any advice is very welcome! Thanks!