found a lump

Well, was the vet aware of his other symptoms like being tired and the panting etc.??  If it was Willow I'd call the vet again and make sure he/she fully understands the symptoms the dog is showing and see what they say. It's not uncommon for them to "keep an eye" on something at first.  But,  ersonally, since he's already showing symptoms of being "ill", I'd want to find out what was going on as soon as possible.  If you wait another month, it could spread or be more difficult to treat. 

If you're not completely comfortable with the discussion with the vet, I'd get a second opinion. 

I would also speak with the vet if you didn't relate those conditions to him/her also, but another thought came to me is if your dog picked up the fact you are distressed over the whole issue and are showing depression, it could also affect your dog in that he picked up your emotions.
Either way, I wish you well and please advise up what follows.
Sending you comforting thoughts.
 

he threw up this greenish yellowish liquid this morning and seems to be a tiny bit better but still is very unenergetic.  i just brought my dog to the vet and all he could do was tell me to come back in a month. do you think he will make me come in and pay again? its just so hard for me to pay for vet bills on my own. 

  Welcome to idog Mee; Dogs will throw up bile when their stomach is empty and it the vomit is yelowish;  if your dog hasn't been eating well that could be what it is. You may want to explain your financial situation to your vet and see if they'll take payments or you could do something for them like cleaning the cages; there are instances where other members have worked out payments with their vet or did some work for them. Did the vet do a thorough examination; listen to your dog's breathing, heart, take his temperature, check his gums for paleness and feel all over his body for other lumps? A word of advice about the lump; don't feel it every day or you'll have trouble telling if it's changed size; wait at least a few days. Jessie had a lump on her side a few years ago that was too small to aspirate and the vet told me to check it once a week for the reason I gave you. She did not have any symptoms of illness though like your dog. You definitely need to tell the vet about your dog's symptoms ASAP; please keep us posted.

Is the lump kind of soft (semi-mushy) and round or is it very hard and possibly irregular shaped?
 
It could just be a fatty tumor which is usually nothing to worry about. Your dogs symptoms could be coming from something different all together. You said that he is 9 years old, so could he possibly be suffering from a touch of arthritis? Or he could be having some heart problems that need maintence medications. There are many possiblities for things that can be treated easily.
I am not making light of his situation or your worry for your fur-baby, but your stress will not help him. Animals are very intuitive and can sense when the ones they love are worried or sick. This can compound any problems that they might be having, so the best thing you can do is to think through this thing with a clear level head to try to figure it out and get him the care that he needs.
If your current vet is not adequately caring for you dog and answering your questions, maybe it time to find a vet that will. There are organizations that will help people that are having financial difficulties with paying for their vet care. I am not sure of the names of all the organizations, but I'm sure that you could google it or maybe someone else here knows.
 
Good luck to you and sending positive thoughts for you and your baby!