Feeling sick after taking sleeping tablets? ?

As I took the second one I kind of gagged and it felt like I was bringing it back up but then I swallowed multiple times and it went down. Now im lying in bed (still not asleep) and my stomach is making weird lurching kind of sounds and I feel a bit nauseous. I'm 14, is this normal? This is the second night I've taken them. The brand is nytol herbal remedy ones ):