"If all else fails, read the instruction manual." I have to remind myself to do the same on many subjects.
Unactivated MMS in water might work if something in the water activates it. If it does, then the CLO2 gas will quickly leave the water into the air. If the dog drinks water with some MMS in the water, it might activate in its stomach, which would be good.
If you used citric acid to activate MMS and gave that to your old dog, I can see why he/she didn't like it. Most humans don't like the taste of citric acid either, and for some, it upsets their stomach. You can add some nice tasting liquid to MMS1 in a syringe so the dog would accept it, even beg for it!
I don't understand why sellers of MMS products continue to sell citric acid when they have 4% HCL. If no one bought citric acid from them, they would soon stop carrying it. Boycott time.
If you can feel the lump, then you can apply CDS and DMSO to that location, externally.
From an antioxidant table: (Antioxidant content in mmol/100g)
www.ncbi.nlm.nih.gov/pmc/articles/PMC2841576/#S1
Oranges, navel = 0.9
Turmeric = 10 to 16
Coconut oil = 1.07