4 days of positive OPK

J
Hi experts! 
I had posted my first near positive OPK on Friday night (top test in picture)..since then I've tested twice a day (3 times on Saturday as i was scared I had ran out of time to BD before S/O home (how wrong i was!) now I have had positives ever since...the bottom test was done a couple of hours ago and looks the strongest but in actual fact the past 5 I have done have been that colour, but faded with time.
In order from top to bottom-
1. Fri 6pm
2. Fri 10pm
3. Sat 8am
4. Sat 2pm
5. Sat 8pm
6. Sun 10am
7. Mon 4pm
Does anyone know why I would have so many positive? Is it normal? I've had painful cramps since thuraday...
My periods are somewhat irregular...
Thanks guys
J x