Good morning to healthcare magic.
Your previous cycle was regular...so don't need to be much worried. Try to relax and cool down. Your last period continued for 3-4 days but blood discharge was less...it is quite normal....so don't think much about that and it is not a infertility
It may be due to stress
or heavy work load on brain (suddenly) also in irregular eating habit.
So maintain your personal hygiene, take healthy diet and sleep well for improvement of health in future.
All the best and if you need extra consultation,then mail me...my id: firstname.lastname@example.org