Melody, It sounds like you are right about teething being the cause of this change in his nursing pattern. You're very wise to have found a way to nurse him, too. Good for you, momma!
I don't think it would be a good idea to start a bottle, either. With patience, you will get through this little spell with him. A nursing relationship will go through many changes as baby grows and a mother who is as determined as you can find information, be creative, and continue to nurse her baby.
First, his weight gain may slow or stop from time to time without being a cause to worry.
A good way to judge if he is getting anything from his short nursing sessions is counting wet diapers. If he has at least six wet (not just damp) diapers a day then he's getting enough.
Your milk may be letting down faster now and the increased flow is too much for him. Check to see if he's swallowing when you think he's not sucking enough. As babies grow, they become much more efficient at nursing and seem to need less.
It is normal for him to start nursing less often -- longer between nursing sessions. Watch him for hunger cues and go by his lead. He won't willingly starve himself.
Have you made any changes in your diet or personal care lately? You or him started taking any medications or different vitamins?
Does he have a cold? Stuffy head or cough? Could it be that breathing is difficult or that his ears are hurting?
Sometimes a change in nursing position can help relieve discomfort. Can you nurse lying down?
As babies grow they also become more aware of and sensitive to their surroundings. Sometimes these disturbances can be eliminated. But it's easier, imo, to teach baby to ignore them. I used to keep pleasant music on in the house so that there was always some sort of noise. This blocked out some of the household sounds & street noise. And I would try covering baby's head/face with a light covering to cut down visual distractions. A couple of mine were prone to 'pop off' and check out every sound and movement.
I hope something in this post gives you an idea that works for you. Sounds like you're doing great, just need to patiently wait out this stage. Please keep us informed of your progress.