Yes. The dog could have rabies.
Pretty sure if it was rabid the pants wouldn’t have stopped it from taking a chunk out of you. And scratches always itch, that’s not always a sign of infection. Still get it looked at, but the Dr will tell you the same thing.
Ruke of thumb for any bite - person or animal is if the skin has been broken to get checked out ASAP.
You don’t know what a person /animal has in terns of illnesses that can be transfered through bodily fluids (like saliva and blood).
I’d also contact a non-emergency police number and report the stray dog to them because you never know who else its bitten already or who it could bite next.
Yes, you should get rabies treatment, and the wound looked at by a doctor, they can give it a good disinfecting.