Sick baby?

Logan

So I’m a first time mom and my girl is 16 weeks on Monday, and the last few days she has barely had an appetite. Going as long as 5 hours during the day between feedings which is very unusual for her. Today when she woke up her cry is very hoarse and now refuses to eat at all even though she’s starving and crying for food. I’m debating taking her to see her doctor, but I have no idea what this could be. She has an appointment next Friday, July 5 for her 4 month checkup. Should I take her in sooner or wait until next week?