If the splinter was removed but the wound has still not healed then this is an indication that there are some shards still left in the wound. Considering that your boyfriend is in constant pain because of this problem, you may have to return to the doctor. One of the signs that you need to look for is the presence of infection in the wound. Being in the foot, an infection here that is not attended to could have some disastrous results. There is a more sinister possibility that you need to also consider, if you know your boyfriends health details. If your boyfriend is immune compromised in any way then this could be a reason for the wound not healing. Diabetes is a condition that can compromise the immune system along with a host of other diseases. If your boyfriend suffers from a problem of wounds taking forever to heal then this is a sign that there is a problem and some blood tests for serum glucose and HIV need to be done.
When a wound occurs, the first step the body takes is to cover the wound up and this is done by clotting of blood. The next stage is to clear dead tissue, damaged tissue, debris, or microbes from the wound – in other words, cleaning the wound. The third step is rebuilding the blood circulation before finally laying a new layer of skin over the wound. In your boyfriend’s case, the wound appears to be stuck in the second stage of healing. This cause’s serious inflammation as the body tries to get rid of any foreign object still stuck in the skin. The pain that is felt can be attributed to this inflammation. When a body part is inflamed, the area swells up as the body tries to expand the area for white blood cells to move in. This swelling can cause the nerves to be pressured. Additionally, the remaining shard is still sharp.
What you need to do now is to administer some painkillers. Ibuprofen is one of the most effective that you can use in this case. You can bolster this by making your boyfriend have lots of feverfew tea with ginger added to it. Apply some hydrogen peroxide to the wound to clean it and then drop some tea tree oil over the wound. Do not cover the wound. In time, this wound will heal with the body naturally pushing the offending shard out, but he would have to ensure that there is no pressure to the wound, or the shard would just go deeper inside.