Can you have IBS, but not all of the symptoms?

Recently, I went to urgent care because for the past month I've had horrible constant indigestion and gas/belching. The doctor told me it sounded like Irritable Bowel Syndrome based on what I told her.

She prescribed me dicyclomine (it relaxes the muscles in your stomach) for 10 days. It's helped a lot, but I still get horrible gas when I lay down, and I can feel my stomach gurgling and will belch a lot for sometime after I get up.

However, I do not have acid reflux, constipation, or diarrhea. Which confuses me as to how this could be IBS, because I don't have all those other symptoms.

I'm worried it's something else. I'm going to see an internal medicine doctor next week. What do you guys think?