chewing is a process where upper & lower teeth come in contact with each other & help in churning the food. so when the upper wisdom tooth is removed, then the lower tooth will not help you in chewing, instead if you keep that lower tooth for many years then it might harm its adjacent tooth because of occlusal drift.
occlusal drift means that when the opposing tooth is absent, the tooth slowly starts moving up.this will probably take few years, so if you can't afford the removal right now then you can get it removed even after 8-10 months or even an year.
For the pain which you are having, usually after wisdom tooth removal pain persists for about a week, but in few difficult cases pain will be there for about 10-13 days. It is a good thing there is no swelling. the dull aching pain will reduce as the healing process slowly completes. But if you are having pain even after 15 days then you should get it checked with your dentist.
For better & fast healing keep that area very clean, you can also use hexidine mouthwash for relief.

You have to find out the cause for the popping of the jaw.Popping of the jaw can be due to varied causes including bruxism/night grinding,improper occlusion or traumatic injury.You should visit your dentist who would give you a definite diagnosis after clinical examination and suggest you a treatment plan accordingly.If the dentist determines that bruxism is causing jaw popping and clicking, he/she may recommend a treatment such as nightly use of a mouth guard, along with elimination of certain foods (i.e. caffeine and alcohol) that are thought to cause teeth grinding and jaw clenching.

hi
this is typical signs of impacted last wisdom lower tooth. you need to get rid of that as soon as possible. you need to improve your oral hygiene and try to do proper mouth rinse and use normal saline water gargles. and for chewing problem you need to visit a maxillo facial surgeon for consultation. regards.