What is an indication that Lucas has an ear infection?

Usually ear pain and fever are good indications of an ear infection (at least for middle-ear infections)

Consider: Adding more detail when asking your next question. For example, what do you know about Lucas, is there any context given, is the question multiple choice? Also, a general Google search will often cover straightforward questions such as this ;)

1) Hearing loss (or decrease in sound volume) in one ear.

2) Earache or ear pain

Explanation:

because i had an ear infection before

activation of phospholipase c (plc) indirectly increases intracellular ions through inositol triphosphate (ip3).