Removing indentation from macro

I've created two macros for my math book project. One is an enumerate environment that numbers problems as "Example 1.1" and so on. The other is a command that writes metadata about each problem to a text file.

The problem is that for some reason when I combine these two macros, there's an unnecessary indentation that I'm not sure how to get rid of.

\documentclass{article}

\newcounter{myenumi}
\renewcommand{\themyenumi}{\textbf{Example \thesection.\arabic{myenumi}.}}
\newenvironment{myenumerate}{%
% stuff for beginning of environment goes here
\setlength{\parindent}{0pt}% don't indent paragraphs
\setcounter{myenumi}{0}% restart numbering
\bigskip% skip a line
\renewcommand{\item}{% new definition of item
\par% start a new line
\medskip
\refstepcounter{myenumi}% advance counter
\makebox[8em][l]{\themyenumi}% print counter to width of 3em, aligned to left
}% end of definition of item
}{% at end of environment
\par% start new paragraph
\bigskip% skip a line
\noindent% don't indent new paragraph
\ignorespacesafterend% ignore spaces after environment
}

\makeatletter
\newwrite\@datawrite
\immediate\openout\@datawrite=\jobname.data

\newcommand\exampledata[3]{%  
\immediate\write\@datawrite{Example \thesection.\theenumi}
\immediate\write\@datawrite{Source: #1}
\immediate\write\@datawrite{Checked: #2}
\immediate\write\@datawrite{Difficulty: #3}
\immediate\write\@datawrite{}}

\AtEndDocument{\closeout\@datawrite}

\makeatother

\begin{document}
\section{A section}

\begin{myenumerate}
\item
\exampledata{A nice book}{yes}{easy}
Show that $a=b$.
\item
\exampledata{Another nice book}{no}{impossible}
Show that $c=d$.
\end{myenumerate}

\begin{enumerate}
\item
\exampledata{A nice book}{yes}{easy}
Show that $a=b$.
\item
\exampledata{Another nice book}{no}{impossible}
Show that $c=d$.
\end{enumerate}

\end{document}

The problem is that for the first items, Example 1.1 and Example 1.2, there's an indentation before the problem statement that I do not want. Could someone help me get rid of it?

Thanks in advance for the help. Here's a picture of the above document.