I am sorry to hear about your hand injury
. With this sort of finding, it is not possible to accurately determine the cause without seeing your skin changes in person. I strongly encourage you to make an appointment with a primary care physician
to help determine how to treat this and whether you need any additional testing.
It is difficult to know exactly what caused your skin prick. It is possible this was caused by another plant amidst the ivy. This could also represent a spider bite. Although some spiders are highly venomous, it is difficult to know what sort could have bitten you without seeing the spider itself. It is possible you pricked your wrist on a nail or other sharp object on the house. In this case, it would be important to know if you are up to date on your tetanus vaccination. It is also possible you suffered a tick bite. Depending on where you live, this could put you at high risk for Lyme disease. Lyme disease often leads to a characteristic skin lesion consisting of a red circle with central clearing, and Lyme disease requires a course of oral antibiotics to treat. I encourage you to see a primary care physician to help determine if any additional course of action is necessary.