I'm sorry to hear about Tivo's weakness and lack of an appetite this morning.
Is he very weak, and thus unwilling to rise, or is he truly unable to get up? If you pinch his toes does he react? If not then he may not feel his feet and cannot rise.
Did his veterinarian think that the swellings in his groin were his lymph nodes?
If so were any other lymph nodes swollen?
Is he neutered?
Was he eating well before he started the medications?
Vetprofen is a nonsteroidal anti-inflammatory that can be hard on an older dog's gastrointestinal lining, leading to irritation and ulcers, as well as tough on his kidneys and liver. That could definitely interfere with appetite.
Some antibiotics can also cause stomach upset, so they too may be playing a part in this.
What sort of testing was done?
Did Tivo have a complete blood count and biochemistry profile?
If the groin swellings were believed to be lymph nodes then a blood test called tick disease panel would be prudent. Tick borne diseases can cause lymph node swelling and weakness/joint pain as well as organ damage, anemia and decreased platelets, so possible internal bleeding.
I think Tivo needs to be rechecked by his veterinarian.
In the meantime at home to try and settle his stomach today you can give either:
1) Pepcid-ac (famotidine) at a dose of one half of a 10mg tablet per 10 to 20 pounds of body weight every 12 hours.
2) Prilosec (omeprazole) at a dose of one quarter of a 20mg tablet per 10 to 20 pounds of body weight every 24 hours.
These will reduce stomach acid and should help if this is related to simple nausea and gastrointestinal irritation from the medications. They can be given for several days if need be.
You can give him pedialyte to drink to replace electrolytes too.
Offer a bland diet mix of 1/3 boiled, lean hamburger (or boiled, white, skinless chicken), all fats and juices drained off the meat, mixed with 2/3 boiled, plain white rice. Feed several small meals a day.
You can also add probiotics to his bland diet mix to rebalance gut bacteria. Good brand name products include Fortiflora, Proviable, or Benebac. They can be found online or at pet stores.
Once she feels better (eating well for 48 hours) start mixing in his regular dog food very slowly, less bland more regular with each day. It should take a week or so to convert him back.
If he begins vomiting and continues feeling poorly such that he continues to be unable to rise it would be best that he see a veterinarian now.
Please let me know if you have any further questions.