Krishnakumar
This looks very much like a tick. If you saw something that was red and small initially but has now grown to become a little black and big, it is most likely a tick. The tick bites dogs and drink blood, very much like mosquito or bed bugs. And they keep attached very strongly to the dog’s skin. To check if it is a tick, see if you can spot 6 small legs, closer to the dogs skin. You can use a tweezer to pluck the tick out, the bite will be strong so pull it right from the place where it is attached.