Yep, it's more likely to be the PPG as 1 in 10 people cannot tolerate PPG on their scalp.
Before trying Dr Lees PPG free minoxidil, try his standard minoxidil (Product Number 500), it contains less PPG than Rogaine and will dry in 10 minutes unlike his PPG free formula which , like Rogaine, takes a long long time to dry (if it ever really does).