Should I contact an attorney before I contact Walmart's injury dept?

You should definitely contact an attorney before you speak with Walmart. Walmart tends to aggressively defend slip and fall cases that occur on their premises and they will likely try to get you sign a release that may terminate your rights to sue. Slip and fall litigation in Pennsylvania is extremely fact sensitive,. The issue of whether Walmart had notice of the slippery or dangerous condition, which caused you to fall is the key hurdle you need to get over to prevail on such a case.