Yes, stitches can get infected. The surgeon
or emergency room doctor
who placed the stitches should examine your arm if you are concerned that they might be infected.
If your doctor put a dressing over the stitches, then you should generally change that once a day. Wash the area over the stitches with regular soap and water once a day, and pat dry. You should not require any more care than that, unless your doctor gave you other instructions.
Signs of infection include red skin, pus forming around the stitches, worsening pain, and fever. It is normal to have some degree of redness around the stitches as they heal, since the natural process of wound healing involves some inflammation around the site. But if the redness is spreading outward around the stitches, or if it is very bright red, then you should see a doctor.
Since you were injured at a building accident, it is also important to make sure your tetanus vaccine is up to date. You should be vaccinated every 10 years to prevent infection with tetanus, which can cause paralyzing muscle contractions and death from breathing muscle paralysis. Talk to your primary care doctor
, who can give you that vaccine.