Indent after fall! HELP!

My son is 9 months and today as I'm doing laundry, he crawls over to the dryer and tries standing up. He ended up hitting his head on the corner of the dryer. He started crying and when I picked him up he had a indent in his forehead right abover his eyebrow. Shortly after, it looks like the indent has went away but seems to look like it's starting to turn purple. I'm beyond scared because I'm a ftm, so I'm not sure what to do. A little bit after it happened he started playing and laughing. Tried calling his doctor but their not open on Thursdays. Am I freaking out to much or do I need to take him to hospital?

I keep replying the fall over and over again in my head. I feel abosultey terrible 😳