See a urologist. There are many causes of abnormal semen analysis and many of these can be corrected or improved. You should see a urologist with an interest in male fertility for further evaluation.
Depends on findings. If the semen analysis reveals simply low counts, dietary supplements of zinc and other natural substrates may be useful. If the size, shape and motility are issues, the treatment may be more difficult. Often these problems can be addressed with in vitro or artificial insemination using your husband'sperm in a concentrated form.