Nut allergy and rash, should I be calling the doctor?

My daughter ate banana bread with walnuts in it today, I didn't give her any pieces with the actual walnuts but she ate 4 or 5 bites of the bread.
Now she has a rash that looks like hives all over her trunk and arms.  She is a little cranky, I don't see any other signs of a problem other than the rash.  
She is 10 months old and we have never given her anything with peanuts because her father, grandfather and unle are all highly allergic.  My husband (her dad) has to carry a kit, and has nearly died from peaunuts.
Is the rash a positive that she is allergic to the walnut in the bread she ate or from something else?  Should I call the doctor tonight or just keep checking on her?

[Want2BeMama]

i would call the doc. she is problably having a reaction to somenthing ...if its not the nuts could it be somenthing else she eate? i got an allergic reaction to a body wash that i used and i had those hives you just described and my dermatologist told me when somenthing like that happens take benadryl i think they have benadryl for kids...but i would defenetly call the doc. it dosent hurt..hope she is ok! good luck.