FitflopWomen's Iqushion Ergonomic Flip-Flops Toe Thong Sandals

Are these genuine fitflop?

Will these loosen. Bought a size 6. (normally am 5), length is fine but they are very tight across the straps.

Are these any good for someone with plantar fasciitis ?

I am a size uk 7 and narrow foot will these be fine for me