Talk with your pediatrician about what's going on. Many times physical problems are easier to diagnose or to rule out, and if they are diagnosed can often be treated easily. Find out if the doctor believes that your son's lack of interest in working with his hands (cutting, coloring, writing) may indicate a physical problem and if some occupational therapy might help.
Another possibility is that your son is not developmentally ready to use his fine-motor abilities to do work in school. If this is the case, your son will become interested in writing and cutting when he is ready. Unfortunately, it's difficult to wait for this readiness when the rest of the children are doing these things, and we tend to want to push the child into doing fine-motor tasks.
If your son seems to be ready, you may want to encourage him this summer to work on his writing and coloring by giving him special crayons and fun markers, blocks, clay, Legos, and finger paint. There are special scissors available in craft stores that cut designs rather than just a straight line, and he might enjoy those as well.