Overdose of metformin

Patient: I was taking metformin (500 mg) pills. My total dosage was 2000 mg per day. this meant 2 tablets in the morning and two in the evening. However, there was a change in the tablet from 500 mg to 1000 mg. This meant I should have been taking 1 tablet in the morning and 1 tablet in the evening. Whatever the reason I missed this change and continued taking 2 tablets in the morning and 2 tablets in the evening for a total of 4000 mg metformin per day for 14 days instead of 2000 mg. What should I be aware of and should I be checked out at an ER? How long will it take to get the extra metformin out of my body?

Symptoms: Loss of appetite, difficult breathing, diarrhea, increased anxiety, low blood sugars