Should I be seek intervention for my 4-year old's diarrhea with blood? His other symptoms are mild.

4 year old boy, no previous history. On Saturday, fever of 38 - 39 all day, not much appetite, tired. Slept OK Saturday night. Sunday moderate diarrhea, lower fever (hovering around 38). Less tired (fluctuating: perked up, then tired again. Never listless or dropping off). Monday, noticed small amount of bloody mucus (< 1 teaspoon, 'redcurrent jelly') at the end of (still loose) stool. Took him to family Doctor (general practitioner, not specialist) who examined him (temperature, chest, palpating abdomen) and was unconcerned, sent him home. Kept him hydrated monday (no vomiting) and some return of appetite (dry toast only).

Today (Tuesday) first thing, stool firmer. Had some cereal with small amount of milk for breakfast. Some hours later, diarrhea returned - this time with more blood (still red) more generally (not just at the end, and not 'redcurrent jelly'). Abdomen still soft. Temperature 37.8.

Not in pain throughout.

Should we go back to family practitioner? Fear that with same tests (temperature, chest, abdomen) we'll have same results -> sent home again.

Advice / provisional differential diagnosis welcome.