Livie gags on anything with texture. I'm talking if we keep trying, she throws up!

What gives? She is 8 months old now, and should be learning to chew right? She gags really bad and vomits when we have to give her tylenol too. It's kinda thick, so I guess it's another texture problem. What can I do to get her to eat small soft chunks? I'm terrified to give her a cheerio like all the other babies eat at first. HELP!!