Since it’s in your nether region mark the edge of the rash with a pen and see if it expands over the next 24 hours. If it grows you need to go see a doc about it. If it stays the same or lessens then you should be good. Some tick bites will be itchy and red for a few days but will otherwise go away. Then again, I got into some small ticks once and ended up having to get on an antibiotic regimen to get rid of an infection in my knee from them. If it gets larger or becomes more swollen, antibiotics might be a good idea.