My husband s second toe is swollen and extremely painfull down to the base there is also two hard bumps one on the side and one on the top of the toe which has a dark circle. He has not injured it, and we could seen no indication of an insect bite though we are not sure.
Here I want to know is he having diabetes? As well do he have any change in sensation for feet or hand? If yes then as per your explanation looks like the circulation to the toe is affected. And he need to do test on lower limb circulation ( dopler test ) . If he does not have diabetes as well no sensory change in feet level then it may be related to block due to vessels for lower limb due to deep vein thrombosis also. Again to conform he has to do dopler test. Here I also suggest to take a test on his complete blood count and cholesterol level also to rule out the blood related things like ESR , and HB, or  cholesterol problem and if there is problem here then he can take treatment as per that.Here it could be possible he does not have any thing above and then it means either there was a insect bite or he might have got hit some whrere but he does not remember. For this he need to check with doctor again and based on physical examination there will be antibiotics with anti inflammatory and pain killer medications will be needed.Here I have given general idea on possibilities since I have not doe any physical examination but I suggest once you check with your doctor with physical examination and few test they will be able to help you more.Take care.