You need to see your gynecologist and make sure that you actually do have a yeast infection. It's possible that you haven't cured the infection because you aren't dealing with a yeast overgrowth at all. Maybe you have a bacterial infection.
The only way to find out is to get a culture. If you find out that you do, in fact, have a chronic yeast infection, then you want to be checked for diabetes. Chronic yeast problems are often caused by diabetes. You will also want to have your insulin levels checked through a glucose tolerance test. High insulin levels cause inflammation and infections throughout the body. If your insulin levels are too high, then switch to a low carbohydrate diet by cutting on simple sugars, breads, pasta, rice, cake, cookies, sugars, and so on.
Also, make sure that you are taking probiotics (such as Primadophilus and bifidobacteria) to make sure that the mucosa inside your body (the tissue that lines your mouth, digestive, urinary, and vaginal tracts) is balanced. Improper flora balance often leads to chronic infections.
Good luck. You should be able to get to the bottom of this (no pun intended). As for your boyfriend's lack of understanding, you may need to go to a couples therapist.
He is apparently personalizing your health problem and taking your refusal to have intercourse as a sign that you don't love or desiire him. He needs to understand that your refusal isn't about him, it's about you, and your pain.
You might try taking time to pleasure him, which would give him tangible, hands on, proof that you do want to make him happy.