Hi, I'm new to this site. I've looked everywhere for answers and have found more honest, helpful information here than anywhere else online.

I would really like another opinion as to what may be going on with my mouth. In July 2013 I had #8 extracted because it shattered inside my crown. A bone graft was placed at the same time because no infection was present. I had no trouble healing, everything went well.
Four months later I went I had a zirconium implant placed, and again, everything seemed fine for a few weeks as I healed. (I took most of a course of antibiotics) At the 4-week mark, I started having some mild pain and irritation in the gum area above the Maryland bridge. Nothing was visible on the outside such as swelling, redness, etc., but the irritation began to grow into pain. I returned to the dentist and he took x-rays, looked at the site, and took off the bridge to examine closely the abutment and gum. Everything appeared normal, with absolutely no swelling,pus, or redness, although there was some tenderness in the area under my nose, and I felt throbbing around the implant area.
I went home with the flipper instead of the bridge, because the dentist thought maybe it was gum irritation from not cleaning under the bridge well. I was puzzled because I thought zirconium implants did not harbor bacteria as much as titanium, and I did brush and floss.
After days with no improvement, I went back to have it looked at again. Still no visible signs of infection, but to me it felt infected. I told the dentist that the pain and throbbing would be very mild in the morning, and build in pressure throughout the day, leaving me in much pain by the evening. He took the implant out, which had not osseointegrated in the 6 weeks it was in. As there was no visible sign of infection, he placed another bone graft immediately, and gave me more amoxicillan.
After a few days my gum had healed up nicely, but the pain continued, even causing the tooth next to it to hurt. They phoned me in a prescription for a more powerful antibiotic, and I started to feel better over a few days. The tooth next to the graft stopped hurting, and it felt like the deep pain was gone. However, at 14 days when I went in for suture removal, I told the dentist I still had some mild pain across the front of the gum, and I get these weird shooting sensations in the graft area. I was told to take it slowly and let it heal. After he gently probed a little in the gum area up under my nose I told him that's where it hurt, and he said that it was normal for there to be local pain at the site of the graft until it healed. After I went home I was in a lot of pain for a couple of days where he touched it.
It is now 18 days past the second graft. Again, I have little pain in the morning, but by evening the bone graft area is throbbing and sometimes I need pain reliever.
My questions are these: how much pain after the bone graft is normal? (After my first graft last summer I didn't have any trouble, but I can't even remember how long the pain lasted) How long should I give this?
why would my zirconium implant fail? Should the dentist have assumed right away when he saw the failure that it was because of infection, and treated me for that first, before putting the graft in?
why does the pain feel mild or non-existent in the morning, but around dinner-time in the evening start to become more intense?

Some other notes: I eat well, (currently on candida-diet and probiotics to help healing), don't smoke, and take calcium, magnesium, Blue-ice codliver blend vitamins, for bone growth. I leave the flipper off most of the time.

I would greatly appreciate any insight into my situation as I can't seem to find satisfactory answers elsewhere. I am weary of the pain and not knowing what is going on. Thank you!