Should I Be Concerned About My Toddler S Recurrent Vomiting, Which Smells Like Vinegar And Causes Breathing Struggles?

My son is 4 year old and last night from around 1.30am was being sick, he hadn t eaten any dinner so it was very liquid like but smelt like vinegar rather than the usual vomit smell. After being sick a lot last night he has been perfectly fine all day today playing and being his usual happy self other than not eating much but he has drank some just not a lot. He s gone to bed tonight at 7pm and woke at 10.15 being sick again, seemed himself after just wanted to go get back into bed. When his bedding was changed and he was cleaned we tried taking him back up at which point he started projectile vomiting, again its mainly liquid and smells like vinegar, he was being sick so much that for a moment he struggled to breathe. Do I worry or do I just hope it plays out and he s fine tomorrow?