Bad night for Nitro

I had a bad night last night with Nitro. He was up in the middle of the night, he was vomiting, I was up at 4:30 with him, he went out then, vomited some, and then when he came back inside, he went back to sleep for a few hours. But again at 7:30 he went out, and was vomiting again.
He’s been ok since then, he hasnt vomited any more, but he refused his breakfast, he did go out for a walk, my dad took him out. I was kinda thinking was it even a good idea for him to go walking, you know because well I thought he might be weak. But he was fine.
I hope he’s going to be ok. I noticed he’s sick a lot at my parents house. He eats grass a lot there. This morning when my dad looked at his vomit he said it looked all white, and there was a lot of grass in it. Hoping he just has a tummy upset and he’ll be ok later on this afternoon.
We’re going to try him with some food again in the afternoon. Hopefully he’ll eat it then. Its totally unlike him to refuse his breakfast, he’s a lab, their tendency is to eat and eat and so the fact he’s refusing his food must mean he’s not feeling well…poor puppy.