One year old started spitting up.

My son is almost 13 months and suffered with bad reflux until he was 8 months and then it stopped completely.

These past 4 days he started spitting up again out of nowhere. Sometimes it is very large amounts! I cannot see my doctor until the 13th, so I took him to the walk in clinic and the doctor told me to try a liquid diet for 24 hours but it didn’t help at all. He hasn’t eaten anything out of the ordinary, he is pooping normal and acting like himself. I am starting to worry. I called the doctor again but have not heard back yet. Has anyone else experienced this?