Ay alam ko that anxious feeling, mama, it's hard to wait, pero good thing your pedia appointment is coming up soon! Honestly, babies do go through phases and sometimes they get distracted or overwhelmed by their surroundings kaya parang nawawala ang smiling, especially if may changes sa environment or routine ninyo, pero since he was so smiley at 4 months, definitely bring this up to your doctor on Wednesday, they can properly check if something's going on or if it's just a phase na dadaan lang. One of my mum friends had a similar worry and it turned out okay, pero peace of mind from your pedia is really what you need right now instead of guessing, kaya just list down your observations (like how he was before, what changed) para maayos mo sabihin sa doctor. Hang in there!