Help for Dog's Swollen Lymph Nodes Needed

Hello, I am new to this forum but am a long-time believer in holistic/homeopathic living. I have a beagle with swollen lymph nodes and am going to try to give as much info as I can think of right now but am sure to miss something. So please be sure to ask me all follow-up questions needed.

• Purebred beagle named Millie
• Dumped at our business after being used as a breeder
• Had heartworm which was successfully treated after we took her in
• Spayed
• Approx. age is 5 years
• Weight 30lbs
• On Revolution for heartworm/fleas/ticks
• Has been on Clavamox for approx. 10 days with about 4 more days to go
• Had thorough dental cleaning yesterday; no extractions
• Previous needle biopsy showed benign lymph node fluid
• Surgical biopsy was taken yesterday while under anesthesia for dental surgery
• Pre-surgical blood work showed no abnormalities in liver or kidney function, white blood cells, or whatever else they check for
• Results will be in 7-10 days
• Biopsy taken on right node, which is noticeably larger than the left node (possibly due to swelling from biopsy)
• Left node is golf-ball size, right node is about double that
• Vet noticed minor swelling about 6 weeks ago, at which point I began monitoring the nodes myself with a noticeable increase within the past 2 weeks
• I can hear her having difficultly swallowing, so if this isn't painful, I know that it is at least uncomfortable for her
• Not lethargic, great attitude, very affectionate, completely pack-oriented, homebody, still loves walks—no major changes in demeanor
• On a pain pill 2x a day for the next few days post-surgery

My concern (and the vet's) is that we had hoped her glands were swollen do to the poor state of her dental disease. However, we both agreed that if there had been dental-related infection her glands would have improved while on the pre-surgical Clavamox. Since they are getting larger, the vet opted to take the surgical biopsy and send it to see what further info we can find.

While we wait for the results, I am researching possible prognoses and would like to put her on a better diet. I will be totally honest and admit that her diet has been very poor. Who knows what she ate in her previous life; they obviously didn't not care for her properly. She had been eating outdoor stuff between the time they dumped her and we took her in—she had worms, etc. Since being with us she's been on dog food, but it has varied. I have been broke the past few months and she's been on Beneful, which is hardly made of top ingredients. However, I am getting back on my feet financially and am making Millie's health a priority.

So while I can't come here with a definitive diagnosis, I believe that improving her diet can only help as we begin the process of figuring out what is wrong with her and put together an eventual plan of action. Should I go with a raw diet? Will a higher quality dog food suffice for now? And what are some basic supplements I can begin adding to her diet to help improve her immune/lymphatic system? Anything you can suggest will be greatly appreciated and I am happy to answer any questions regarding anything I've missed. Please help!