Hi Kate and Lincoln. Welcome. Your future posts won't need approval so post away. And you're definitely not out of the loop. We have many members from the UK! I'm glad you found the community helpful.

Here are some posts from other members concerned about their Tripawd vomiting after surgery. Many are in relation to chemotherapy, many are not. There's a few in there that had vomiting issues caused by the NSAID. So maybe that's the cause of what's going with Lincoln?

I'm sorry to hear that he had to join our club. It's not an easy path as you know but things do get better! Lincoln has good mobility overall which is great news. Laying on the cold floor isn't unusual, many new Tripawds will do that because it feels good on the swelling around the incision. 

The vomiting and blood clot is concerning of course. Your vet's strategy sounds reasonable to me. I'm not a vet, but that makes sense she would pull the Metacam and add the omeprazole. Did they run any tests on him while he was there? Sounds like she suspects acid reflux? Here's a post we wrote about GERD in dogs. Do any of his symptoms sound like the ones mentioned in the post?

As for pain control, it's hard to say if that would be affecting him in this way. What is the dosage of Gabapentin that he's taking? Sometimes too little pain control can cause anxiety and restlessness, but then again too much can do that as well. It's a balancing act. Overall his pain management sounds good. I would check with your vet to see if you can space out the Gabapentin and paracetemol so that he's not having all of it in his gut all at once.