Went walking to the park and back with my husband and my doggie Sugar earlier today. Was fine at…

Went walking to the park and back with my husband and my doggie Sugar earlier today. Was fine at first when we got back but an hr later started feeling nausated from everything except water. Its still that way to. Even though i feel hungry i cant really eat because it makes me feel sick. The walking was good for me and i stayed hydrated...so why do i feel this way now? Kinda confusing.