Yes burnout is a reality. Try to introduce a scheduling system, and operate your Fiverr business as you would a real life business. Have time slot for recreation and family as well as a time slot for work.
You have to work hard to get more orders and deliver on time then your delivery time will climb up. Or you can wait 60 days and see your stats back on 100% If you see that you cannot deliver in time its better to ask the buyer for more time through the resolution centre. This will completely help keep your stats crisp clean.