Derek has no idea what's going on, but whatever it is it is Not Good, capitalized with italics. Underlined several times. Isaac's text, combined with Erica's vague and upsetting "Something's up with Isaac :(?" (the frowny face did nothing to soothe Derek's nerves), Derek's all but panicking.

He pulls up to the curb in front of the school with a screech and got out to look for Isaac, sniffing the air to try and scent out his mate.