I assume symptoms came on quickly and therefore need to be addressed quickly to prevent/minimize tissue loss or damage.
As for its relation to alcohol--there are a lot of reasons for infections and vascular problems, some related to alcohol and others not. Most alcoholics are also malnourished and can therefore have weakend immune systems. Depending on the caloric intake (alcohol has 7kcal/g--somewhere between carbohydrates and fat), it can also lead to problems with weight and fats. The typical results of chronic alcoholism
include loss of clotting factors made in the liver, build up of toxins, such as ammonia and bilirubin
, processed by the liver, poor brain function (some are reversible and others are not), bleeding ulcers, and skin changes
Indirectly, compromised skin can be an entry site for bacteria
and malnutrition can weaken the immune system, making infection more likely. Also, poor clotting factors can increase bleeding. If this happens to be a large hematoma (collection of blood), it could be related, but that is much less likely. If he has a major clot in the vessels making his hand swell and turn colors, that is often related to diabetes
or other vascular diseases which are only indirectly related to alcohol.
Regardless of the cause, your husband needs to get immediate care of his hand and long-term care of his alcoholism. You, too, should seek support with a group such as al-anon. You need to learn how best to help him get the care he needs...And sometimes that means making painful decisions not to help him in other ways.