I'm sorry that your question wasn't answered in a timely manner. Please let me know if you still need help. May I have an update on Soldier, please?
In the order of severity, I would place his problems as so:
1. Collapsing, breathing heavily, difficulty rising
2. Drinking excessively
3. Breathing and panting heavily
4. Hiding under the bed and licking his front paws
Collapsing can indicate profound weakness as would occur with severe anemia, the hypoxia (lack of oxygen to his tissues) from cardiopulmonary disorders, severe osteoarthritis, and any number of metabolic diseases.
Drinking more than usual (polydipsia) and urinating a higher volume of urine (polyuria) are danger signs for quite a few disorders. These include both hepatic and renal insufficiencies, urinary tract infection involving the kidneys, diabetes mellitus and Cushing's disease (both will also cause increased hunger (polyphagia)), hypercalcemia (increased serum calcium level), electrolyte (sodium, potassium, chloride) imbalances, and the rarer Addison's disease, diabetes insipidus, and brain tumor involving the hypothalamus. Soldier's vet will need to perform a thorough physical exam including diagnostics in the form of blood and urine tests in order to clarify what those symptoms are signifying.
Excessive panting can represent both medical and behavioral problems. It's often seen with elevated ambient temperature, exercise, anxiety, or perceived pain. To confound the diagnosis further, it's also seen with fever, narcotic administration, glucocorticosteroid (prednisone, e.g.) therapy, Cushing's disease, hyperthyroidism, hypocalcemia, pheocromocytoma (an adrenal gland tumor), cardiac disease, tachyarrhythmias (fast irregular heart rates), brain disease and obesity.
Hiding under the bed constitutes reclusive behavior indicative of a dog not feeling well. Licking of the paws may represent an allergic dermatitis.
I understand your financial constraints at this time. Regrettably, there's likely to be more than one thing going on with Soldier at his age and only his vet will be able to sort these out for you. Please respond with further questions or concerns if you wish.