Your local school district offers free speech evaluations. Call the local school district special education department and ask about a speech evaluation for your preschooler. The local public school offers special needs services for kids age 3 -21. (speech is considered a special need service). Head Start also offers speech services and evaluations.
He is also only three. He may still be growing, a late bloomer. And that's OK. You can play with him and encourage discussions. A for telling you about this day, some 3's just get distracted easy and move on after an incident. What happened at 11 AM could seem light years away for a three year old. I had plenty of 3's over my years teaching at HS that rarely spoke, and the next school year were little chatterboxes.
Receptive language means the ability to understand or comprehend language heard or read. Expressive language means being able to put thoughts into words and sentences, in a way that makes sense and is grammatically accurate.
http://nspt4kids.com/parenting/10-activities-develop-expressive-language/