painful big toe

My left big toe is hurting at the knuckle joint, and on its left side. I noticed this two days ago, and thought at first that I must have broken it, though I couldn't imagine how. The range of motion is very limited (maybe 1/2" up and down) and it hurts to walk if I put any pressure on it. Slightly swollen and reddish in the affected areas.

I'm a male, 59 years old, southwest USA, not overweight, healthy in general.

Any thoughts on what this might be/ what to do about it?. I soaked the foot in hot water last night, and have taken a few ibuprofen tablets today. Neither did much.

thanks